Goldenrain is the common name, spelled as one word or two, for the tree also known as Koelreuteria paniculata. Shanghai-born Ming Fay, whose artwork often incorporates edible plants (as well as the occasional migratory food fish), kindly wrote to confirm that live goldenrain trees are planted next to his sculpture, one each on two corners of Prince St.; their namesake pods are shown below. Since then I've seen the trees from sidewalks in Greenpoint and Morningside Heights, too. Reportedly, goldenrain seeds are edible when roasted, but gathering enough pods would be very labor-intensive. Perhaps Q can come up with some clever time-saving solution.
"Goldenrain Pier" (the artwork's full name)
Ming Fay, 2000
Prince St. at 38th and 39th Aves., Flushing, Queens